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TS5A3159: Peak current rating for very short duration at start up?

Jason Rubadue
Intellectual 1165 points
Part Number: TS5A3159


The TS5A3159 datasheet specifies that the maximum ON-state peak current is 400mA (for 1-ms duration < 10% duty cycle). However, my customer's inrush current during the switching operation could exceed the peak current rating for a short period of time (e.g., nanoseconds to microseconds).

Without a current limiting resistor and ferrite in series, they measured 16A peak of inrush current (I'm assuming a quick exponential decay due to the capacitive nature of the load, but I don't have a scope shot).  With a 10 Ohm resistor and ferrite bead they can keep the inrush current below the part's 400mA peak current rating, but the parts induce a voltage drop that effects the load. 

Could you help us understand if the peak current rating (400mA for 1ms duration <10% duty cycle) is based on thermals, power, or something else?  My customer is trying to determine the peak current and duration that they’re allowed to subject the part to (over temp) without degrading it.  Can you please help us determine what current*time product is acceptable?


 

  • 0
    TI__Mastermind 45625 points

    Jason,

    We cannot grantee that exceeding the absolute maximum current ratings won't cause permeant damage or reliability issues with the TS5A3159.

     

    The maximum allowable current passing through the device is specified in the abs max table based on several considerations for both short term and long term effects of current.  Here is an example of the 3 types of design considerations used when creating the abs max specification.

    The 1st consideration is based on long term reliability of the device and is temperature dependent.  This is basically measuring the maximum DC current that can pass through the device for X number of years without issue. 

    The 2nd consideration is similar to the 1st but for AC signaling

    The 3rd consideration is where your question lies. How much current can the device handle even with a short duty cycle?  As you notice that for a short period of time the TS3A3159 can handle more current than the long term DC rating 200mA.  We can grantee in the table above that current up to 400mA for 1ms, 10% duty cycle will not cause permeant damage or long term reliability issues.  It is possible that the device will survive high current ratings with even shorter durations listed in the datasheet but there will be a point where the device will fail, but we cannot grantee beyond what is in the absolute maximum rating.   

    Thank you,

    Adam